This is obviously a poor response. First, there is no major #whitelivesmatter movement claiming that white lives are at risk primarily due to black racism and police. If there were, as there is for #blacklivesmatter, invoking white on white crime might be appropriate. Perhaps even more importantly, while most white homicide victims were killed by other whites, they were not disproportionately killed by whites relative to blacks. Black on black violence is disproportionate.
After we take into account the fact that around 93% of hispanics are classified as white in FBI statistics, we can say that the general population the FBI classifies as white outnumbers the general population classified as black by a ratio of about 6.2 to 1, using the 2010 census. The FBI data also finds that the population of people who killed a white person has white people outnumbering black people by a ratio of.... 6.1 to 1. So, any given black person is about equally likely to kill a white person as any given white person.
However, the story is different for black on black violence. If we take into account that, in 2013, when we look at people who killed a black person in 2013, there were 11.9 times more blacks than whites. In addition, in the general population has whites outnumbering blacks by a ratio of 6.2 to 1. That means that any given black person is about 73.8 time more likely to kill a black person than any given white person.
To summarize, black on black crime is a unique problem. The main fact to take away from this is that any given white person is about equally likely as any given black person to kill a white person. On the other hand, any given black person is about 73.8 times more likely than any given white person to kill a black person. So, yes, black on black crime is a unique problem in a way that white on white crime is not.